DE69924624T2 - LAYER FOR DETERMINING A CHEMICAL SUBSTANCE, CHEMICAL SAMPLE AND ASSOCIATED METHOD OF MANUFACTURE - Google Patents

Description

Technical field of the invention

The The present invention relates to a film for detection a chemical species, to a chemical sensor (sensor), the a film according to the invention to a method of making a chemical sensor (Probe) comprising such a film, as well as a method for improvement the temporal stability and the reproducibility of an electrical signal coming from a inventive film for the detection of a chemical species.

The Invention is applicable in all fields where detection a chemical species based on the change of an electrical Property of a sensitive material under the influence of the detected chemical species.

To the facilities in which the electrical properties of a sensitive material, such as e.g. a movie to Detection of a chemical species include, for example, the conductometric chemical sensors, the electronic components of the transistor type with field effect and the detector electrodes in a liquid medium.

In these properties is the film, i. the active material, in Shape of a thin Films ago, for example, has been prepared by the Langmuir-Blodgett method by covalent grafting, by sequential deposition of superposed multilayers, by chemisorption or by any classical method of depositing films, in particular of thin Film.

Around For example, to make a chemical sensor, this film can be arranged on an insulating substrate, with thin metal electrodes which is performing a measurement of electrical conductivity enable the movie.

State of the art

The The field of conductimetric chemical sensors has turned into two independent of one another Directions developed depending on whether the sensitive element a mineral or metallic material, usually made a metal oxide, or of an organic material.

The most commonly used mineral material, for example in the context of gas sensors, is tin oxide SnO ₂ . This type of material has been the subject of numerous studies for more than 30 years. It has the advantage that it has good chemical and thermal stability. In contrast, it has a poor intrinsic selectivity, which is related to the fact that the detection procedures take place at the joints of the grains. The selectivity is modulated by the type of chemical species that are present on the surface of the grains and whose relative concentration varies with temperature. On this detour, therefore, a certain selectivity is determined as a function of the operating temperature of the sensor. Effects on device selectivity have also been observed when certain additives, such as Pd, Pt, Ag, are incorporated into the material or when chemical treatments, such as with SO ₂ , are performed during the manufacture of the material. The processes associated with detection in this type of material are due to the modification of the potential barrier layer present between adjacent grains. The exact mechanisms are still little known. Often, catalytic effects or oxidation-reduction phenomena are indicated.

As far as the organic materials are concerned, there are still very few concrete embodiments, and among these are exclusively called polymeric materials. The use of the organic material in devices for conductimetric measurements seems to be severely limited by temporal instability phenomena and also by the large scatter of electrical properties found in a same series of samples. This is initially the persistence of an electrical measurement error (drift), which is certainly due to the nature of the materials themselves. In addition, the overall system has very high resistance values due to the use of purely organic materials. Finally, the fact that the material is responsible both for the detection of chemical species and for the transduction (conversion) of the corresponding electrical signal leads to a considerable limitation with regard to the type of molecules that can be used. Namely, only molecules can be used which lead to electrically conductive materials, and their sensitivity is in the We considerably limited to pollutants which have pronounced oxidation-reduction properties.

It is thus difficult to produce systems that are both electric conductive as well as selective for one Proof and this is one of the negative points that the organic Materials with the mineral materials in common.

In the document by H. Wohltjen et al., "Colloidal Metal Insulator Metal Ensemble Chemistoristor Sensor ", reprinted in "Analitycal Chemistry ", volume 70, no. 14, 15 July 1998, pages 2856-2859, is a film on chemical Detection described, which consists of mineral nanoparticles and organic molecules, which have been grafted onto said nanoparticles so that they are an organic crown around the mentioned nanoparticles form. This detector film is not specific.

Summary of the invention

aim In particular, it is the problem of the present invention to solve the problems of the present invention To solve the prior art and a movie for to find evidence of a chemical species, in particular a high temporal stability the conductometric measurements, a high detection selectivity, a low dispersion of electrical properties at the same Series of samples are detected, as well as a low electrical Deviation, a controlled resistance and a high sensitivity having.

Of the film according to the invention, that is defined in claim 1, has interaction properties with the chemical species to be detected and electrical properties and is characterized in that it contains mineral nanoparticles, hereinafter referred to as "nanoparticles", and organic molecules includes.

According to the invention can Nanoparticles have the task of essentially electrical Ensure the film's properties and the organic molecules can do that Task, essentially the interaction properties between the film and the chemical species to be detected guarantee.

The organic molecules, which have the task, essentially the interaction properties between the film and the chemical species hereinafter referred to as "organic Interaction molecules ".

According to the invention organic molecules grafted on the nanoparticles so mentioned that they around the nanoparticles form an organic crown, and organic molecules which have the task, the interaction properties between ensure the film and the chemical species to be detected can mixed with the nanoparticles, around which an organic crown or grafted onto the organic molecules are those that have an organic crown around the nanoparticles mentioned form.

According to the invention It is the organic molecules that are referred to Nanoparticles are grafted to organic molecules which essentially have the task of creating an organic crown around the Nanoparticles to form around, or it is organic molecules which have the task, both an organic crown around the nanoparticles around as well as interacting with the organic interaction molecules to connect the chemical species to be detected, the latter molecules hereinafter referred to as "bifunctional organic molecules ", or a mixture of them.

The nanoparticles are, for example, nanoparticles which comprise at least one member selected from the group of platinum, gold, silver, CdS, TiO ₂ .

The Nanoparticles can for example, have a size which is between 1 and about 100 nm in diameter, or they may be one Size of about 1 to about 50 nm in diameter or even a size of about 1 to about 10 nm in diameter, this particle size being homogeneous or may be heterogeneous, preferably homogeneous.

The organic molecules which have the function of ensuring the interaction properties of the film with the chemical species to be detected can comprise or consist of a molecule selected from the group phthalocyanine, tetrapyridinophthalocyanine, thiophene, oligothiophene, Porphyrin, erythrosine, crown ether, azacrown ether, cryptophan, cyclodextrin, linear or branched alkyl of 1 to 12 carbon atoms, benzene, derivatives of these molecules which are unsubstituted or substituted by one or more chemical interaction functions with the chemical species to be detected.

at the grafted onto said nanoparticles organic molecules they are organic molecules, which essentially have the task of creating an organic crown to form around the nanoparticles, i. not the job have, with the chemical species to be detected in interaction to step. The function of these molecules will be described below. These organic molecules can include or consist of a molecule, selected from a group comprising, for example, a linear or branched one Alkyl having 1 to 12 carbon atoms, an aryl, unsubstituted or substituted by one or more chemical functions for fixation on the mentioned nanoparticles. These chemical functions for fixation on said nanoparticles are described below.

at the grafted onto said nanoparticles organic molecules can It also involves bifunctional molecule that exhibit one hand at least one chemical function for fixing to said Nanoparticles, and on the other hand, at least one chemical function to bind to the organic molecules, which is not the task have the interaction properties of the film with the detected to ensure chemical species.

It is for those skilled in the art will readily understand that the bifunctional molecules organic molecules could be, which are grafted onto the nanoparticles and on which organic Interaction molecules grafted or "grafted on".

The at least one chemical function for fixing to said Nanoparticles is preferably a chemical function, for example the formation of a covalent bond or a strong bond to the mineral nanoparticles allows. She can, for example selected are selected from a group comprising a thiolate, an isonitrile, an amine, a trioctyl phosphate and a pyridine.

The at least one chemical function to form a bond to the organic interaction molecules can be selected from a group comprising a pyridine, an amine function, a carboxylate function, an acidity function, an alcohol function, an aldehyde function, an isocyanate function, a Isothiocyanate function, a -COCl function.

According to the invention, the at least one chemical interaction function with the one to be detected chemical species, for example, are selected from a group, which comprises a pyridine, an amine function, a carboxylate function, an acidity function, an alcohol function, an aldehyde function, an isocyanate function, an isothiocyanate function, an ester function, a -COCl function.

The Bi-functional organic molecules can include a molecule selected from a group that includes a thiophenol, a linear or branched one Alkylthiol having 1 to 12 carbon atoms and an arylthiol.

at the film of the invention For example, it could be about a movie in which the on the selected nanoparticles grafted organic molecules can from the group comprising 4-mercaptoaniline, 4-mercaptopyridine, N-aminoalkanethiol and mercaptohydroxyalkane or a mixture of it.

Of the inventive film can be, for example, a film in which the nanoparticles platinum nanoparticles are, and grafted onto said nanoparticles organic molecules that make up an organic crown that are molecules above can.

In the film of the invention can For example, the nanoparticles may be platinum nanoparticles on which organic molecules grafted from 4-mercaptoaniline.

In this movie can the organic molecules, which have the task, the interaction properties between to ensure the film and the chemical species to be detected, for example, thiophene or Erythrosine molecules be, taking these molecules grafted onto the 4-mercaptoaniline molecules could be, or you can For example, be tetrapyridinophthalocyanine molecules, these molecules with the Nanoparticles onto which the 4-mercaptoaniline is grafted can be mixed.

at the tetrapyridinophthalocyanine may be, for example copper tetra (hexyloxycarbonyl) phthalocyanine to give copper tetraoctadecyltetrapyridinium [3,4-b: 3 ', 4'-g: 3' ', 4' '- l: 3' '', 4 '' '- q] porphyrazine bromide, or cobalt tetraoctyltetraamidophthalocyanine.

As described above define in the film according to the invention the mineral nanoparticles are essentially the electrical ones Properties of the film. In particular, they have the role of forming the charge carriers, passing through the detector film, for example, between two electrodes of a chemical sensor, and they play in a sense the Role of relay electrodes within the organic molecules of the film. For example, if the film of the invention in a chemical Sensor is used, which comprises a substrate and electrodes, is the contact resistance between the film and the electrodes, which ensures the recovery of the electrical signal's considerable diminished towards a purely organic film of the prior art. Furthermore is the film of the invention characterized by a better temporal electrical stability than a purely organic film of the prior art. Because namely the electric conductivity in which film is essentially provided by the nanoparticles, become the organic molecules less needed for the electric conductivity as in a purely organic film.

In the film of the invention have organic molecules essentially the task, the interaction properties between to provide the film and the chemical species to be detected, i. it is the interaction of the organic interaction molecules with the to be detected chemical species, the electrical conductivity modified by the film, which is essentially ensured by the nanoparticles, causing a modification of the resistance or the electrical conductivity of the Films is effected. Namely, in the film of the present invention, the mineral part plays the role of a transductor, since it supplies the charge carriers, which is the electrical conductivity guarantee. Inside the film these charge carriers pass a nanoparticle after the others, traversing the organic part. In this area is the interface between the detection and the transduction. Overcome the charge carriers the organic barrier layer consisting of the organic molecules a tunnel effect or a jump line process. In both make must overcome an energy barrier layer become. In the absence of the chemical species to be detected the value of this energy barrier layer and the value of its physical Characteristics a value that determines the electrical conductivity of the Films determined. If a chemical species that is organic Interaction molecules can react in which the medium surrounding the film is present, are the properties of this energy barrier layer, which overcome the charge carriers have to, modified and thereby is also the electrical conductivity of the material modified.

Of the Evidence of the modification of the electrical conductivity of the film allows the Evidence of an interaction between the chemical species that and the organic interaction molecules of the Films and thus the proof of said chemical species.

The The present invention thus provides a film, the mineral Nanoparticles and organic molecules in which the electrical Properties of the film and the interaction properties with the Essentially, the chemical species to be detected are separated from each other are.

According to the invention can Interaction properties of the film with the chemical to be detected Species the result of one or more interactions of the organic Interaction molecules all or only part of it with the proof be chemical species.

Furthermore can (can) according to the invention the interactions) the organic interaction molecules with the detected chemical species is the result of one or more, preferably reversible, interaction types, e.g. a hydrogen bond, an ionic bond, a Van der Waals interaction, an electrostatic bond or dipolar interaction or more of these interactions.

one the benefits of using organic molecules that a reversible bond or interaction with the to be detected chemical species, is that the film easily regenerates can be for to be ready for a new proof of the chemical species. If The bond is little reversible or irreversible, can be a chemical or physical treatment may be required to film regenerate.

According to the invention, this interaction can be more or less specific for the to be detected Thus, it will be readily understood that the detection selectivity of the inventive film is largely a function of the interaction specificity of the organic interaction molecules comprising it with the chemical species to be detected.

So is, for example, a film according to the invention which comprises organic interaction molecules which for one given chemical species are very specific, very specific for the said predetermined chemical species, and a film according to the invention, which includes organic interaction molecules that are responsible for a family of chemical species is specific to the said Family and the like

Therefore It depends on the nature of the organic interaction molecules that be very versatile, possible, the detection selectivity of a Sensor or an electrode, the (the) film of the invention wearing, strongly orient. While The purely organic materials of the prior art essentially are sensitive to chemical species that are pronounced Possess oxidation-reduction properties, with the proven chemical species in this case the electrical intrinsic conductivity modified directly of the organic material, the film according to the invention, which has a hybrid structure, also sensitive to chemical species which have no special oxidation-reduction properties.

The Invention is therefore novel compared to the prior art in particular because it provides a hybrid film that is very specific Detection of extremely variable chemical species allowed by a clever selection of organic interaction molecules with the to be detected chemical species.

One film according to the invention, made of a simple mixture of nanoparticles with organic molecules and especially the organic interaction molecules, can become an incomplete controlled distribution of these two species and thus to one poor electrical conductivity lead in the movie. The dimensions of the organic and mineral areas may be inhibitory for one good proof of the chemical species through the film. So that Charge carrier, which are formed by the nanoparticles and the electrical conductivity guarantee, from the organic molecules and especially "seen" by the organic interaction molecules and thus the electric conductivity In the movie is sufficient and stable, it may be important that the mixture of nanoparticles and organic molecules so homogeneous as possible is, even with very small dimensions.

Around For example, a percolation of mineral nanoparticles or the "mineral Phase "to prevent it is appropriate, a relationship from nanoparticles to organic molecules, avoiding them Permitting percolation. This percolation phenomenon can namely prevent the organic interaction molecules from their Roll in the movie completely play.

Furthermore can be determined by controlling the structure of the film, i. the succession of organic and mineral sections, proof of a chemical species are optimized by the film.

Also alternate in the film of the invention the nanoparticles preferably with the organic molecules in the Way that a homogeneous mixture is formed on the nanoscale.

at a first embodiment The present invention therefore provides organic molecules in the Way grafted onto the said nanoparticles that they are around the nanoparticles form an organic crown, and the organic interaction molecules can with the nanoparticles on which an organic crown has been formed is, be mixed.

at a second embodiment of the present invention the organic molecules, which have the function, the interaction properties of the To ensure films with the chemical species to be detected, on organic molecules grafted to an organic crown around said nanoparticles form around.

These embodiments of the present invention allow a restriction of the aggregation of the nanoparticles, to ensure and even control a homogeneous alternation of organic and mineral areas in an area that even in the nanomer order can lie.

It this results in several strategies of application of the present Invention.

at a first application strategy, that of the first embodiment According to the present invention, the nanoparticles of organic molecules surrounded, which essentially have the task of an organic Crown around them to form. These organic molecules are preferably grafted onto the nanoparticles by covalent bonding. The grafting can be achieved by any chemical Reaction known to those skilled in the art organic molecule to graft a metal or mineral, for example by use of pre-synthesized particles covered by a labile molecule are that, then is replaced by the organic molecule to be grafted, or by Synthesizing the mineral particles by reducing a corresponding salt in the presence of the grafting organic molecule, wherein the organic molecule to be grafted has a chemical function for Has fixation, as indicated above.

at This strategy involves the interaction of organic molecules with the chemical species to be detected with those of an organic Crown surrounding nanoparticles mixed so that homogeneity in the smallest possible Scale, preferably of the order of magnitude of nanometers.

These The first strategy of the present invention allows aggregation nanoparticles, but it does not always allow a homogeneous alternation of nanoparticles, by their organic Crown are surrounded, and the organic interaction molecules in the Ensure film.

The enclosed 1 illustrates in schematic form the simple juxtaposition of nanoparticles with the reference character α, which ensure the transduction, and of organic molecules with the reference character β in a film according to the invention.

at a second strategy, that of the second embodiment of the present Invention, as stated above, the organic interaction molecules are organic molecules grafted around an organic crown around nanoparticles.

In In this case, the organic molecules, the form an organic crown around the nanoparticles to bifunctional organic molecules, as indicated above: on the one hand they have an or several chemical functions for fixing by covalent bonding to the nanoparticles and on the other hand have one or more chemical functions to form a bond to the organic Interaction molecules on. In this second strategy, the bifunctional organic molecules grafted onto the mineral nanoparticles after any any chemical reaction, as well known to those skilled in the art is and is intended to be an organic molecule that has a chemical function of fixing it, grafting it on, on a metal and / or a mineral, for example, beforehand used synthesized particles covered by a labile molecule are that, then is replaced by the organic molecule to be grafted, or by one the mineral particles by reduction of a corresponding one Salt synthesized in the presence of the organic molecule to be grafted, wherein the organic molecule to be grafted has a chemical function for Has fixation, as indicated above.

The Nanoparticles on which the bifunctional organic molecules grafted are sometimes also referred to below as "functionalized nanoparticles".

The grafted bifunctional organic molecules thus have a "free" chemical function to Training a bond opposite the organic interaction molecules.

The organic interaction molecules can grafted or "grafted over" onto the top bifunctional organic molecules by simple and classical chemical reactions, as applied in organic chemistry become two organic molecules to connect with each other, which have chemical functions, such as they are named above.

Thus, according to the invention a film of functionalized nanoparticles "pre-fabricated" and, depending on the chemical species, which is to be detected may be a suitable organic molecule, for example one of the above grafted onto the bifunctional organic molecules of the "previously prepared" film become.

The following equation (I) schematically shows a chemical reaction of grafting an organic interaction molecule onto a functionalized platinum nanoparticle. This equation shows in particular in schematic form the grafting of a thiophene molecule which has an acid chloride function onto a free chemical NH ₂ function of a bifunctional organic molecule 4-mercaptoaniline which is grafted onto a platinum nanoparticle:

Thiophene molecule

The enclosed 2 illustrates in schematic form a functionalized nanoparticle with the reference numeral 1 , It includes a mineral nanoparticle 3 , on the bifunctional organic molecules 5 which form an organic crown, for example using the two strategies of the present invention described above.

In this 2 F1 represents a chemical function of the bifunctional organic molecule, for example, as mentioned above, by which the organic molecule is fixed to the nanoparticle, and F2 has a chemical function of forming a bond with the organic interaction molecules with those to be detected chemical species, as indicated above, wherein F1-F2 stands for the bifunctional molecule.

The enclosed 3 shows a chemical reaction for grafting an organic molecule 7 which has the function of ensuring the interaction properties with the chemical species to be detected, on bifunctional organic molecules 5 forming an organic crown around the nanoparticles 3 around in accordance with the present invention. The nanoparticle 3 , which includes the organic crown F1-F2, is the one as in the 2 wherein the grafting is performed with the function F2, in this case a function of forming a bond to the organic interaction molecules 7 represents. In this 3 F3-M is an organic interaction molecule where F3 is a bonding function to the chemical function F2 and M is the chemical interaction function with the chemical species to be detected. This becomes a functionalized particle 9 receive.

The enclosed 4 illustrates in schematic form the alternating sequence of nanoparticles and organic molecules on a nanometer scale in a film according to the invention. Namely, the film of the present invention can be regarded as a film composed of elemental building blocks, which are, for example, the functionalized nanoparticles 9 which is in the 3 are shown schematically. The arrow that contains the functionalized nanoparticles 9 traverses, indicates a possible trajectory of the charge carriers in the film. The use according to the invention of functionalized nanoparticles makes it possible to ensure a controlled homogeneity of the interaction between the organic interaction molecules and the mineral nanoparticles on the smallest possible scale, ie on the nanometer scale.

The 5 Fig. 12 shows a schematic representation showing the separation of the electrical properties of the film of the invention provided by the mineral nanoparticles from the interaction properties of the film with the chemical species to be detected, provided by the organics explained molecules.

In this figure, the reference numeral refers 3 on a mineral and / or organic nanoparticle, the reference number 9 refers to a functionalized nanoparticle, reference numeral M refers to a chemical interaction function with a chemical species to be detected, and the zigzag arrow represents in schematic form the interaction between this chemical function and the chemical species to be detected Modifying the electrical conductivity of the film, which is essentially ensured by the nanoparticles. This modification is determined by measuring the resistance of the film between two electrodes E in this figure.

• – eine Verbesserung der zeitlichen Stabilität und der Reproduzierbarkeit des elektrischen Signals, das durch Verwendung eines partiell mineralischen Materials bestimmt worden ist,
• – eine Erhöhung der elektrischen Leitfähigkeit des Materials dank der Anwesenheit des mineralischen Teils,
• – eine Aufrechterhaltung der Nachweisempfindlichkeit und einer potentiellen Selektivität, die organischen Materialien eigen ist, aufgrund der Anwesenheit von organischen Molekülen in der Struktur,
• – eine Trennung der Nachweisfunktion von der Transduktionsfunktion, Funktionen, die jeder chemische Sensor aufweist, durch Verwendung von mineralischen Teilchen, die für die Transduktion verantwortlich sind, und von organischen Molekülen, die für den Nachweis verantwortlich sind,
• – eine Verbesserung der Zuverlässigkeit der Ansprechempfindlichkeit eines Sensors, der einen erfindungsgemäßen Film umfasst, gegenüber einer nachzuweisenden chemischen Species.

Because of its novel composition and novel structure, the film according to the invention has numerous advantages over a film of the prior art, in particular:

• An improvement in the temporal stability and reproducibility of the electrical signal determined by using a partially mineral material,
• An increase in the electrical conductivity of the material thanks to the presence of the mineral part,
• A retention of detection sensitivity and potential selectivity inherent in organic materials due to the presence of organic molecules in the structure,
• A separation of the detection function from the transduction function, functions that each chemical sensor has, by using mineral particles that are responsible for the transduction, and organic molecules that are responsible for the detection,
• An improvement in the reliability of the responsiveness of a sensor comprising a film according to the invention to a chemical species to be detected.

Of the inventive film is preferably a thinner Movie, he can be any of the expert in the field known methods for producing such a film using, for example, the Langmuir-Blodgett method, by covalent grafting, by sequential deposition of successive multilayers, by spin-coating, by dip coating, by chemisorption or by any means Another technique, for example, starting from a solution that Nanoparticles comprises grafted onto the organic molecules according to the invention have been.

For the expert is easy to understand, that the film must have a thickness suitable for use, which he fed becomes.

This For example, film may be placed on an insulating substrate be that with thin ones Metal electrodes, which is the measurement of its electrical conductivity allow to create a chemical sensor.

The Invention also relates to a process according to claim 16 for the preparation of a chemical Sensor, which includes an insulating substrate, a film for detection a chemical species and at least one metal electrode, wherein the method comprises a step for producing a film according to the invention, a step for depositing this film on the insulating substrate and a step for depositing at least one metal electrode between the substrate and the film or on the substrate isolated movie.

below will also a method for improving the temporal stability and the Described reproducibility of an electrical signal that determines was using a film to detect a chemical species that on an insulating substrate, which in certain zones of his surface was provided with metal electrodes, was deposited, the Method characterized in that it comprises a stage for producing a film according to the invention in such a way that the electrical properties of the film, which is essentially through the mineral nanoparticles are provided by the interaction properties of the Films containing the chemical species to be detected which are essentially through organic molecules are provided, a separation step of the film on the insulating substrate and a deposition step at least one metal electrode between the substrate and the film or on the film deposited on the substrate.

In In the aforementioned method, the electrodes are preferably under deposited on the film, i. on the insulating substrate in front of the Deposition of the film.

The above methods can Furthermore include a step consisting of interposing at the interface between the insulating substrate and the film according to the invention and / or at the interface between the electrodes and the film according to the invention at least one monomolecular Applying an intercalation layer consisting of organic molecules covalently with the substrate or with the electrodes are connected, said molecules having an organic group, which the properties of the mechanical and / or electrical Contact between the film according to the invention and the metal electrodes and / or between the film of the invention and the substrate can.

The Intercalation layer between the substrate and the film of the invention can be arranged, allows control of the type and quality of between the substrate and the film and between the electrodes and the film formed interface. By applying this intercalation layer covalently attached to the Substrate and is bonded to the electrodes, according to the invention, the surfaces of the substrate and the electrodes in terms of their physico-chemical properties be made identical by the presence of organic groups, which can improve the contact with the film according to the invention. These Intercalation layer thus allows to achieve a more homogeneous Deposition of the film according to the invention on the entire surface of the substrate. If the two surfaces in terms of their physicochemical Properties are identical, in particular the discontinuities of active materials in the zones where one arrives from the substrate to the electrodes. If in the case of Materials obtained by spin-coating or by the Langmuir-Blodgett method have been separated (this is the order in which this Improvement is achieved), this point gains a central importance, because it is about the production of materials by Grafting or automatic sequencing.

The Presence of this intercalation layer also allows the Quality improvement the mechanical contact between the substrate and the electrodes on the one hand and the film according to the invention on the other hand.

The Difference in terms of the expansion coefficient between the The mineral substrate and the film according to the invention can namely partly cause for difficulties be that can occur during execution a reliable one electrical measurement.

Finally allowed the presence of this layer improves the quality of the electrical contact between the substrate and the film of the invention.

• – die ersten Moleküle sind an der Grenzfläche zwischen dem Substrat und dem erfindungsgemäßen Film angeordnet, und die zweiten Moleküle sind an der Grenzfläche zwischen den Metallelektroden und dem erfindungsgemäßen Film angeordnet.

This layer may be formed of identical molecules or comprise different molecules. When composed of different molecules, these are generally of two types and are arranged as follows:

• The first molecules are arranged at the interface between the substrate and the film according to the invention, and the second molecules are arranged at the interface between the metal electrodes and the film according to the invention.

These Arrangement allows the consideration the different nature of the insulating substrate and the metal electrodes for the Formation of covalent bonds between the substrate and the first molecules and between the electrodes and the second molecules.

in the Generally, the insulating substrate is made of a material the silica comprises, for example, pure silica, fused silica, quartz or glass, and the first molecules are over silicon atoms bound to the substrate. In this case, the first molecules can be silane- or siloxane derivatives having the property by fixed a siloxane-type covalent bond on the substrate to be able to.

in the In general, the metal electrodes are made of a precious metal, for example, gold, platinum or an alloy Base of gold or platinum, and between the second molecules and The electrodes may form a covalent bond, for example via sulfur or nitrogen atoms.

worin bedeuten:

• – R¹ ein Halogenatom oder eine C₁-C₄-Alkoxygruppe,
• – R² und R³ unabhängig voneinander ein Halogenatom, eine C₁-C₄-Alkoxygruppe oder eine C₁-C₄-Alkylgruppe,
• – R⁴, R⁵ und R⁶ unabhängig voneinander eine einfache Bindung oder lineare, aliphatische oder aromatische Kohlenwasserstoff-Abstandhaltergruppen, die Heteroatome, ausgewählt aus O, S und N, und/oder Substituenten, ausgewählt aus Amid-, Amin-, Ester- und Harnstoff-Gruppen, enthalten können, und
• – Y¹, Y² und Y³ unabhängig voneinander ein Wasserstoffatom oder eine organische Gruppe, ausgewählt aus CH₃, CH=CH₂, CN, NCO, NCS, OH, SH, NH₂, COOH, CONH₂, COCl, und Phenyl-, Triazol-, Imidazol- und Pyridyl-Gruppen.

Suitably, the first molecules have one of the following formulas:

in which mean:

• R ^{1 is} a halogen atom or a C ₁ -C ₄ -alkoxy group,
• R ² and R ³ independently of one another represent a halogen atom, a C ₁ -C ₄ -alkoxy group or a C ₁ -C ₄ -alkyl group,
• R ⁴ , R ⁵ and R ^{6 are} independently a single bond or linear, aliphatic or aromatic hydrocarbon spacer groups containing heteroatoms selected from O, S and N, and / or substituents selected from amide, amine, ester and urea groups, and may contain
• - Y ¹ , Y ² and Y ^{3 are} independently a hydrogen atom or an organic group selected from CH ₃ , CH = CH ₂ , CN, NCO, NCS, OH, SH, NH ₂ , COOH, CONH ₂ , COCl, and phenyl , Triazole, imidazole and pyridyl groups.

In These formulas have the alkyl or alkoxy groups used preferably 1 or 2 carbon atoms.

In these formulas, the group R ¹ and optionally the groups R ² and R ³ are leaving groups which allow the anchoring of silicon to the substrate. The groups Y ¹ , Y ² and Y ³ are groups which improve the contact properties or allow other reactions.

The above-mentioned Y groups include hydrophobic groups (CH ₃ , CH = CH ₂ , phenyl), hydrophilic groups (COOH, OH, NH _2, and SH) and groups which can react with the film of the present invention, for example, by complex formation in the case a pyridyl or triazole group, or by condensation in the case of an NH ₂ or COOH group.

The selection of the groups Y ¹ , Y ² and Y ³ depends in particular on the technique ultimately used for the deposition of the film according to the invention. For the Langmuir-Blodgett technique this is essentially the hydrophilic character (Y = OH, SH, NH ₂ ,...) Or the hydrophobic character (Y = CH ₃ , CH = CH ₂ , phenyl,. that is crucial. For the covalent grafting and the multilayer technique, the type of Y depends on the intended reaction type. For example, for a condensation reaction with a carboxylic acid, Y is an amine, for complexation with a metal, Y may be a pyridine or a triazole.

When R ¹ , R ² and R ^{3 represent} a chlorine atom and when it is desired to introduce a hydrophilic group into the first molecules of formula I, II or III, it is preferred to use initially a first molecule in which Y ^{1 is} CH = CH ₂ , then chemically modify the molecules by reacting the allyl group with a reagent which can introduce into the end of the chain a hydrophilic group COOH, OH, SH or NH ₂ . Reactions of this type can be carried out according to methods described by Wasserman et al in "Langmuir", 1989, 5, pp. 1074-1087.

• – R⁹ SH oder NH₂,
• – R¹⁰ und R¹¹ unabhängig voneinander eine einfache Bindung oder lineare, aliphatische oder aromatische Kohlenwasserstoff-Abstandhaltergruppen, die Heteroatome, ausgewählt aus O, S und N, und/oder Substituenten, ausgewählt aus den Amid-, Amin-, Ester- und Harnstoff-Gruppen, enthalten können, und
• – Y'¹, Y'² und Y'³ unabhängig voneinander ein Wasserstoffatom oder eine organische Gruppe, ausgewählt aus CH₃, CH=CH₂, CN, NCO, NCS, OH, SH, NH₂, COOH, CONH₂, COCl und Phenyl-, Triazol-, Imidazol- und Pyridyl-Gruppen.

The second molecules that can be fixed to the noble metal metal electrodes are generally thiol, bisulfide, or amine molecules that conform to the following formulas: R ⁹ -R ¹⁰ -Y'1 (IV) and Y'2-R ¹⁰ -SSR ¹¹ -Y'3 (V) in which mean:

• R ⁹ SH or NH ₂ ,
• R ¹⁰ and R ¹¹ independently represent a single bond or linear, aliphatic or aromatic hydrocarbon spacer groups, the heteroatoms selected from O, S and N, and / or substituents selected from the amide, amine, ester and urea Groups, may contain, and
• - Y ' ¹ , Y' ² and Y ' ^{3 are} independently a hydrogen atom or an organic group selected from CH ₃ , CH = CH ₂ , CN, NCO, NCS, OH, SH, NH ₂ , COOH, CONH ₂ , COCl and phenyl, triazole, imidazole and pyridyl groups.

In In this case, the anchoring of the molecules to the electrodes via S-metal or N-metal bonds.

The Selection of the formulas (IV) and (V) respectively molecules hangs too from the method that finally for the Deposition of the film according to the invention is applied. If this material according to the Langmuir-Blodgett method is deposited, thus the group (s) Y 'is (are) selected so that it is (are) hydrophilic or hydrophobic.

In the case, that the film of the invention by covalent grafting or by a multi-layer method is deposited, hangs the type of groups Y 'of the intended reaction type. If you have a condensation reaction between the active material and the intercalation layer, Y 'can be an amine group when the active material comprises a carboxylic acid group. If the reaction provided a complexing reaction with a metal is, can the group (n) Y ' Ligand, which can complex this metal complex, for example a pyridyl or triazole group.

In the abovementioned formulas (I) to (V), the spacer groups which can be used for R ⁴ , R ⁵ , R ⁶ , R ¹⁰ and R ^{11 can} especially be groups of the formula (CH ₂ ) _n , where n is an integer from 1 to 30, preferably from 1 to 17 represents.

worin p für eine ganze Zahlung von 1 bis 6 steht,
oder es können aliphatische Kohlenwasserstoffgruppen verwendet werden, die einen oder mehrere Amid-, Harnstoff-, Amin- oder Ester-Substituenten aufweisen.It is also possible to use groups which consist of oligomers of the formula:

where p stands for a whole payment from 1 to 6,
or aliphatic hydrocarbon groups may be used which have one or more amide, urea, amine or ester substituents.

• a) Abscheidung einer monomolekularen Schicht der genannten ersten organischen Moleküle auf einem Siliciumdioxid umfassenden isolierenden Substrat, wobei die ersten Moleküle kovalent an das Substrat gebunden sind und mindestens eine organische Gruppe aufweisen, welche die Kontakteigenschaften mit dem erfindungsgemäßen Film verbessern können,
• b) Abscheidung von ebenen Metallelektroden auf bestimmten Zonen des auf diese Weise behandelten Substrats,
• c) Abscheidung einer monomolekularen Schicht der genannten zweiten Moleküle auf den Metallelektroden, wobei die zweiten Moleküle kovalent an die Elektroden gebunden sind und mindestens eine organische Gruppe aufweisen, welche die Kontakteigenschaften mit dem erfindungsgemäßen Film verbessern können, und
• d) Abscheidung des erfindungsgemäßen Films auf der gesamten Anordnung, bestehend aus dem Substrat und den auf diese Weise behandelten Elektroden.

In a first embodiment of the method according to the invention, which allows the formation of an intercalation layer composed of two types of molecules, the method comprises the following successive stages:

• a) depositing a monomolecular layer of said first organic molecules on an insulating substrate comprising silica, the first molecules being covalently bonded to the substrate and having at least one organic group which can improve the contact properties with the film of the invention,
• b) deposition of planar metal electrodes on certain zones of the substrate thus treated,
• c) depositing a monomolecular layer of said second molecules on the metal electrodes, wherein the second molecules are covalently bonded to the electrodes and have at least one organic group which can improve the contact properties with the film of the invention, and
• d) deposition of the film according to the invention on the entire assembly consisting of the substrate and the thus treated electrodes.

at this embodiment the method according to the invention can the first and second molecules correspond to the above formulas (I) to M. In the case, that the film according to the invention The Langmuir-Blodgett method has been deposited, the organic groups Y and Y 'of the first and second molecules be different, but preferably of an analogous nature, to the surfaces of the substrate and the electrodes in terms of their physicochemical To make properties identical. These organic groups can be hydrophobic Be group or hydrophilic groups. In the case of making a Multi-layer structure need the groups Y and Y 'are identical be with the film of the invention to respond, who subsequently or with any other intercalation layers react to form a multilayer structure by chemical Bonds.

The Reactions can those of complexing type, wherein the organic group for example, a ligand of the complex, or they may be such be of the condensation type, for example, an ester amide bond and the like. to build.

at a variant of this first embodiment of the method according to the invention become the first molecules so selected that they attach the adhesion of the metal electrodes of a precious metal promote the substrate and the temporal stability improve the overall layout.

In this case, the first molecules used are a silane or siloxane substituted by a hydrophilic group, an amine or a thiol, for example molecules of formulas (I), (II) or (III) in which Y is NH ₂ or SH group, wherein the radicals Y can form covalent bonds with the electrodes which are subsequently deposited on the treated substrate.

These embodiment the method according to the invention is applied to the generation of a hydrophilic surface state on the insulating substrate and on the metal electrodes.

• a) Abscheidung einer Schicht von ersten Molekülen, die eine hydrophile Gruppe aufweisen, wie z.B. Amin oder Thiol, auf einem Siliciumdioxid umfassenden isolierenden Substrat,
• b) Abscheidung von Metallelektroden auf bestimmten Zonen des so behandelten Substrats,
• c) Abscheidung einer Schicht von zweiten Molekülen, die eine hydrophile organische Gruppe aufweisen, ausgewählt beispielsweise aus OH, SH, NH₂ und COOH, auf den Metallelektroden und
• d) Abscheidung eines erfindungsgemäßen Films auf der so behandelten gesamten Anordnung.

In this variant, the method comprises the following successive stages:

• a) depositing a layer of first molecules which have a hydrophilic group, such as, for example, amine or thiol, on an insulating substrate comprising silicon dioxide,
• b) deposition of metal electrodes on certain zones of the substrate thus treated,
• c) depositing a layer of second molecules having a hydrophilic organic group selected, for example, from OH, SH, NH ₂ and COOH on the metal electrodes and
• d) deposition of a film according to the invention on the entire arrangement thus treated.

The selection of a silane or siloxane comprising SH or NH ₂ groups in this process allows the adhesion of the deposited metal electrodes to the treated substrate to be improved. This improved adhesion property is specifically described by Goss et al. In "Analytical Chemistry", Vol. 63, No. 1, 1991, pages 85-88.

The molecules used in this variant of carrying out the first embodiment of the method according to the invention can correspond to the abovementioned formulas (I) to M, in which the radicals Y are NH ₂ or SH and the radicals Y 'are OH, COOH, NH ₂ or SH stand.

• a') Abscheidung einer Schicht aus einem Silan oder Siloxan, das durch eine Amin- oder Thiol-Gruppe substituiert ist, auf einem isolierenden Substrat, das Siliciumdioxid umfasst, wobei die Schicht die Rolle eines Haftungspromotors für die Metallelektroden an dem Substrat spielt,
• b') Abscheidung von Metallelektroden auf bestimmten Zonen des so behandelten Substrats,
• c') Abscheidung einer Schicht von organischen Molekülen, die über Schwefel- oder Stickstoffatome an die Elektroden gebunden sind, auf den Metallelektroden,
• d') Oxydation der Anordnung mit Ozon, um die organischen Moleküle auf dem Substrat und auf den Elektroden zu eliminieren,
• e') Abscheidung einer monomolekularen Schicht von organischen Silan- oder Siloxan-Molekülen, die eine organische Gruppe aufweisen, welche die Kontakteigenschaften gegenüber dem Film aus dem aktiven Material verbessern können, auf der gesamten Anordnung und
• f') Abscheidung des erfindungsgemäßen Films auf der so behandelten Anordnung.

In a second embodiment of the method according to the invention, an intercalation layer consisting of a single type of molecules is fixed on the substrate and on the electrodes by carrying out the following successive stages:

• a ') depositing a layer of a silane or siloxane substituted by an amine or thiol group on an insulating substrate comprising silica, the layer playing the role of adhesion promoter for the metal electrodes on the substrate,
• b ') deposition of metal electrodes on certain zones of the substrate thus treated,
• c ') depositing on the metal electrodes a layer of organic molecules bound to the electrodes via sulfur or nitrogen atoms,
• d ') oxidation of the assembly with ozone to the organic molecules on the substrate and on the Elek eliminate electrodes,
• e ') deposition of a monomolecular layer of organic silane or siloxane molecules having an organic group which can improve the contact properties with the film of the active material, on the whole assembly and
• f ') deposition of the film according to the invention on the thus treated arrangement.

In the stage (a ') this Can process the for the improvement of the adhesion of the metal electrodes to the substrate used organic molecules correspond to the above formulas (I) to (III).

In of step (c ') this Method, organic molecules of the thiol, Amine or bisulfide type, for example the molecules that corresponding to the formulas (IV) or (V), deposited as in the Embodiments described above then subjecting the arrangement to an oxidation treatment Ozone, which causes the organic molecules to be destroyed. In the following stage (e ') However, you can not only on the insulating substrate, but also on the metal electrodes organic molecules, which consist of silanes or siloxanes exist and covalent bonds not only between these molecules and the substrate, but also between these molecules and form the electrodes.

In the stage (e ') can one also molecules of the formula (I), (II) or (III) and a uniform surface state obtained on the substrate and the electrodes.

It It is believed that the deposition of silane or siloxane on the metal electrodes by the preceding oxidation treatment after the formation of a covalent bond with the sulfur or nitrogen atoms allows becomes.

These second type of implementation the method according to the invention is particularly suitable for the Production of multi-layered structures because of chemical bonds between those in step (e ') deposited molecules and a film according to the invention, whose electrical properties are to be measured, formed can be.

to execution the method according to the invention can the stages of deposition of silane or siloxane on the insulating Substrate are carried out using classical methods, for example, such as those described by Goss et al. in "Analytical Chemistry", Vol. 63, No. 1, 1991, pages 85-88, and by Brzoska et al. In Nature, vol. 360, 1992, Pages 719-721, and by McGovern et al in "Langmuir", 1994, vol. 10, No. 10, pages 3607-3614, are described.

These generally consist of placing the substrate in a solution of Silane or siloxane immersed in a suitable solvent. This is preferably apolar, for example toluene, in the case of silanes.

The applied temperature depends from the silane or siloxane used.

The Deposition of the metal electrodes can also be classical Procedure performed are, for example, such as are customary for the production of thin Electrodes are applied, for example by vacuum evaporation or sputtering.

The Deposition of molecules Thiol, disulfide or amine type can be carried out using classical methods as described by Bain et al in "Am. Chem. Soc.", 1989, 111, pages 321-335 are.

Of the inventive film can subsequently are deposited on the insulating substrate using one of the classic methods well known to those skilled in the art are, for example, one of the aforementioned methods.

If the film of the invention on the substrate using the Langmuir-Blodgett method vertical transmission is deposited, this deposition can be performed starting from a solution the nanoparticles and the organic molecules of the invention, wherein the said solution Furthermore comprises one or more amphiphilic molecules, e.g. a fatty acid. The amphiphilic molecule is a transmission promoter.

The The present invention also relates to a chemical Sensor, characterized in that it is an insulating Substrate, a film according to the invention and at least one measuring electrode made of metal.

The at least one metal electrode is preferably between the substrate and the film, i. under the film, arranged.

Of the Sensor can also at the interface between the substrate and the film according to the invention and at the interface between the electrodes and the film according to the invention at least one monomolecular Include intercalation layer, which consists of organic molecules, the covalently bound to the substrate or to the electrodes, wherein the named molecules have an organic group which the mechanical and / or electrical contact properties between the film from the active Material and the metal electrodes and between the film from the improve active material and the substrate.

The organic group of molecules the intercalation layer may be included among the hydrophilic groups, the hydrophobic groups and the groups that form a chemical bond across from train the film become.

The molecules the intercalation layer, which is at the interface between the substrate and the film of the invention arranged, the so-called first molecules, may be different from the molecules of the Intercalation layer, which is at the interface between the electrodes and the film according to the invention, the so-called second molecules, are arranged.

These molecules can for example, those as described earlier in the method according to the invention have been described.

The Substrate and the electrodes can be those as described above.

Further Characteristics and advantages of the present invention will be apparent the reading the description of the following embodiments and the information in the accompanying drawings, which of course the Merely explain the invention without restricting it.

Short description of drawings

1 shows in schematic form the juxtaposition of nanoparticle regions and organic molecule regions in a material according to the invention;

2 illustrates in schematic form a mineral nanoparticle grafted onto organic molecules forming an organic crown according to the present invention;

3 Figure 2 illustrates the chemical reaction of grafting an organic molecule having the function of providing the properties due to the interaction between the film and the chemical species to be detected, to organic molecules forming an organic crown around the nanoparticles of the invention;

4 shows in schematic form the alternating sequence of nanoparticles and organic molecules on the nanometer scale according to the present invention;

5 illustrates in schematic form the separation of the electrical properties of the film provided by mineral nanoparticles from the interaction properties of the film with the chemical species to be detected provided by organic molecules;

6 Fig. 12 is a graph showing, for two sensors of the present invention, the separation of transcription properties and detection properties in a film of the invention comprising no organic interaction molecules with the chemical species to be detected, and in a film of the invention comprising organic interaction molecules with the chemical species to be detected;

7 shows a diagram showing the responsiveness of two chemi Fig. 10, which shows the separation of the transcription properties and the detection properties in a film prepared according to a second embodiment of the present invention;

8th Fig. 12 is a graph showing the selectivity of a sensor of the present invention versus variable dose organic vapors as a function of the organic molecules contained in the film of the present invention;

9 Fig. 12 is a diagram illustrating the orientation of the selectivity of a sensor of the present invention exposed to toluene, triethylamine and acetic acid;

10 represents a diagram which illustrates the electrical stability of a sensor according to the invention;

11A Fig. 12 is a graph showing the reliability of a sensor according to the present invention over a period of 9 months, showing the reproducibility of the measurement of the detection of a chemical species with a sensor according to the present invention, wherein the responsiveness with respect to the first exposure was calculated;

11B Fig. 12 is a graph showing the reliability of detection of a chemical species from two identical chemical sensors for detection of the same chemical species;

12A FIG. 12 is a diagram explaining the change of the resistance of a film according to the invention as a function of the distance between the electrodes of a sensor according to the invention; FIG. and

12B FIG. 12 is a diagram explaining the change of the resistance of a purely organic film as a function of the distance between the electrodes of a sensor.

example 1

Production of platinum nanoparticles, which are surrounded by an organic crown

300 mg of platinum tetrachloride are dissolved in 75 ml of hexylamine (C ₆ H ₁₃ NH ₂ ) in a 500 ml flask. The resulting solution is an orange-colored platinum salt solution. It will be referred to as Solution 1 below.

300 mg of sodium borohydride (NaBH ₄ ), a reducing agent, are dissolved in a first stage in a mixture of 20 ml of water and 20 ml of methanol. After complete dissolution of NaBH ₄ , 20 ml of hexylamine are added to give a solution 2.

330 mg of the disulfide of 4-mercaptoaniline ((SC ₆ H ₄ NH ₂ ) ₂ ) are dissolved in a mixture of 15 ml of methanol and 15 ml of hexylamine to give a solution 3.

At time t = 0, solution 2 (NaBH ₄ ) is mixed with the platinum salt solution (solution 1) with vigorous stirring. The mixture or the reaction medium takes on a deep brown color after a few seconds, and at time t = 20 seconds, the disulfide solution (solution 3) is added to the medium. At time t = 3 min, 30 s, 200 ml of water are introduced into this reaction medium. After 15 minutes, the mixture is transferred to an ampoule and decanted. The isolated organic phase is washed 6 times with 200 ml of pure water.

The Volume of the organic phase is then in a rotary evaporator at a temperature of 35 ° to reduced to 3 or 4 ml. It is then transferred to a centrifuge tube in which 300 mg of the disulfide of 4-mercapto-aniline 1 dissolved in 15 ml of ethanol, and stir for one night left before centrifuging. The supernatant liquid, the surplus contains the disulfide, is eliminated and the bottom of the tube remains a black one Precipitate back. This precipitate is cleaned with 15 ml of ethanol for 2 minutes, then centrifuged again. You get one black precipitate and a supernatant Liquid, which also contains particles. The precipitate is washed with ethanol and then with diethyl ether, before being dried under vacuum for 2 hours. The thus obtained Product contains 20 mass% organic material and 80 mass% platinum.

Example 2

Reaction to Grafting of functionalized nanoparticles

at these grafting reactions are simple and classic reactions, as applied in organic chemistry become.

20 mg of nanoparticles are dissolved in a minimum volume of a suitable solvent, for example in dimethyl sulfoxide or N-methylformamide. The molecule to be grafted is selected depending on the selectivity that one wants to impart to the sensor or film. For example, in the case of an NO ₂ sensor, an erythrosine or thiophene molecule containing a chemical function suitable for the reactivity of the chemical function F ₂ present on the platinum particle is used. For example, if function F2 (cf. 3 ) is an amine function, the erythrosine or thiophene molecule has an aldehyde or acid chloride or isothiocyanate function. The reaction is then carried out in the presence of a large excess of the molecule to be grafted, for example 20 mg of platinum nanoparticles prepared in Example 1 are used by 4-mercaptoaniline containing 20% by mass of 4-mercaptoaniline corresponding to 4 mg. For example, 10 equivalents of the erythrosine or isothiocyanate molecule added directly to the solution of nanoparticles to be grafted. In this example, the reaction is carried out at ambient temperature for 12 hours. The grafted particles are then isolated by addition of a non-solvent in large excess (for example, acetonitrile or chloroform) and the particles are separated by centrifugation. Following the application of classical characterization methods in organic chemistry, such as UV spectroscopy, visible or infrared light spectroscopy, or nuclear magnetic resonance spectroscopy, classical purification steps are performed if necessary. These purification steps may include, for example, re-dissolution in pure dimethyl sulfoxide and reprecipitation of the particles with a non-solvent.

Example 3

manufacturing a sensor according to the first strategy of the present invention

First you put a solution of freshly synthesized particles, for example those as described in Example 1. One weighs 5 mg of product which are dissolved in 10 ml of dimethylsulfoxide to give a solution of 0.5 mg / ml of particles.

In order to produce the film according to the invention containing the nanoparticles with an organic crown and molecules which are responsible for the detection according to the Langmuir method, the method is continued as follows: 0.5 ml of the particle solution, to which For example, 0.05 ml of a solution of 3 × 10 ^-4 mol of phthalocyanine in chloroform is added. The mixture is then completed with pure chloroform corresponding to 0.95 ml in the present example, to give a total volume of 1.5 ml. An amount of this solution suitable for the dimensions of the cuvette is distributed, for example 1.2 ml solution on a cuvette of 6.5 cm × 45 cm. The spreading volume is 0.6 ml. This solution is then spread on the surface of the water contained in the Langmuir cuvette, then the film is compressed at the selected transfer pressure.

ever according to the applied transmission technique, i.e. horizontal transmission or vertical transmission, this pressure is low, it is For example, 2 mN / m, or is higher and is for example 16 mN / m.

In the case a horizontal transmission become the substrates that are equipped with their electrodes or not, to the bottom of the Langmuir cuvette in spaced about 1 mm from the surface before expansion. After compressing the film, the level of the cuvette is lowered and the film is deposited on the substrates with their Electrodes are equipped or not. This operation will increased as often as necessary, if you want to increase the number of layers that build up the material. The vertical transmission gets in the classic way at a speed of about 0.5 cm / min.

Example 4

manufacturing a sensor according to the second strategy of the present invention

at The second strategy of the present invention is the solution of Nanoparticles containing molecules are grafted, which have the function, the interaction properties of the film with the chemical species to be detected, in a suitable solvent, for example, in dimethyl sulfoxide. The concentration this solution is on the order of magnitude of 0.5 mg / ml of grafted nanoparticles.

As at the first strategy contains the for the distribution used solution Chloroform, for example 2/3 volume fraction. In case of a horizontal transmission can the dissolution solution contain only grafted nanoparticles. For example, you mix 0.5 ml solution of grafted nanoparticles with 1 ml of pure chloroform, taking one the spreading solution gets and you spread out a lot of that solution, the dimensions the cuvette corresponds, for example, 1.2 ml solution for a cuvette of 6.5 cm × 45 cm. Before spreading the solution become the substrates that are equipped with their electrodes or not equipped, placed on the ground at a distance about 1 mm from the surface of the water, and you drive as in the case of the first strategy.

In the case of a classical vertical transfer, if it is not possible to transfer the Langmuir film, which consists only of grafted nanoparticles according to the present invention, the propagation solution usable for the transfer may be an amphiphilic molecule, for example a fatty acid, other than grafted nanoparticles. contained in a suitable proportion. Such a solution can be prepared, for example, by adding 0.5 ml of the solution of grafted nanoparticles at a concentration of 0.5 mg / ml in dimethylsulfoxide with 0.03 ml of a solution of 10 ^-3 M ω-tricosenoic acid in chloroform and Add 0.97 ml of pure chloroform. The amphiphilic molecule serves as a transfer promoter and allows horizontal transfers to be made in multiple layers, for example six layers on the substrates that are equipped or not equipped with their electrodes. After transfer, the amphiphilic molecule can be eliminated by washing the sensor with a suitable solvent, such as chloroform.

Example 5

In This example becomes the above-mentioned first embodiment a chemical sensor comprising a film according to the invention comprises, using the following steps:

1) Silanation of the substrate

at for The molecule used for this silanation is octadecyltrichlorosilane.

First cleans one carefully the substrate by means of basic soap, then rinsed 10 times with demineralized Water. Subsequently One makes hydrophilic by treatment in a Piranha solution, in which it is a mixture of hydrogen peroxide and sulfuric acid in one volume ratio of 3: 7, at a temperature of 150 ° C for 1 h, then rinsing 10 once with demineralised water and dried under nitrogen in a drying oven at 100 ° C.

Subsequently, the thus treated substrate is immersed for 30 minutes at ambient temperature in a solution containing 10 ^-3 mol / l of octadecyltrichlorosilane in toluene.

you receives in this way, a substrate modified by a layer of molecules is the hydrophobic terminations exhibit.

2) Deposition of gold electrodes

These is carried out using classical vacuum evaporation methods and In this way interdigitated gold electrodes with a Thickness of 500 Å (50 nm) deposited in the form of 20 layers (combing) with a length of 5 mm and a width of 150 mm at a distance of 150 mm be formed from each other.

3) functionalization the electrodes

At this stage, dodecanethiol is deposited on the gold electrodes. This deposition is performed so that the electrode-covered substrate is immersed in a solution of 10 ^-3 mol / l dodecanethiol in ethanol for 12 hours at ambient temperature. This results in a binding of the molecules to the gold electrodes, these molecules having a hydrophobic finish, such as the previously fixed to the substrate silane.

4) Deposition of the film according to the invention

The Deposition of this film is carried out according to the Langmuir-Blodgett method, as described by S. Palacin and A. Barraud in "Colloids and Surfaces", 1991, 52, p 123-146, is described. In this way, 14 layers are deposited, with a thickness of 200 Å (20 nm).

Example 6

In This example follows the above variant of the first one embodiment a chemical sensor comprising a film according to the invention for producing a layer having a hydrophilic finish.

In In this case, the substrate is prepared as in Example 5, then is on this a layer of (3-mercaptopropyl) trimethoxysilane using the method described by Goss et al in "Analytical Chemistry", 1991, 63, pp. 85-88 Process deposited.

To For this purpose immerse the substrate in a solution consisting of 400 g of propanol and 10 g of water containing 10 g of (3-mercaptopropyl) trimethoxysilane contains.

Subsequently, gold electrodes are deposited on the substrate thus treated by working as indicated in Example 1, then this electrode is covered with a layer of bis (2-hydroxyethyl) disulphide by placing the substrate in a solution of 10 ^-3 mol / l of this disulfide is immersed in ethanol for 24 hours at a temperature of about 20 ° C. In this way one obtains a substrate which has hydrophilic terminations (thiol terminations) and electrodes which likewise have hydrophilic terminations (OH terminations).

The thus treated substrate may be used to carry out the deposition of the film according to the invention Application of the method described in Example 5 used become.

It it is clear that the production according to the invention an intercalation layer attached to the substrate and to the electrodes is covalently bonded and has hydrophilic groups on the surface, the stability of the sensor in dependence greatly improved by the time.

Example 7

In This example follows the above-mentioned second embodiment a chemical sensor comprising a film according to the invention includes, i. you lead a complementary one Oxidation stage after the modification of the substrate or the electrodes through a silane and through a thiol and you then on the arrangement of a dodecanethiol from.

The First stages of the process consist of taking the substrate treated, then the deposition of the metal electrodes and the functionalization the metal electrodes performs, by looking for the silanation of the substrate (3-mercaptopropyl) trimethoxysilane as used in Example 6 and then the Electrodes modified with dodecanethiol as indicated in Example 5. In this way you get a substrate covered by silane molecules attached to the surface have an SH group, and gold electrodes with dodecanethiol are covered.

Then you lead Oxidation by ozone, by this oxidation in an apparatus, which forms ozone by irradiating oxygen with ultraviolet light for half Hour through. Under these conditions, the hydrocarbon chains the previously deposited organic compounds destroyed and then can a silane is deposited on the array of substrate and electrodes by silanization using octadecyltrichlorosilane as in Example 5 performs.

After that you notice that the surface the electrodes as well as the surface of the substrate bad Wettability properties with water, a contact angle across from Water of 115 ° C on glass and from 110 ° C on gold. This result confirms that one has a homogeneous modification the entire surface of the substrate with octadecyltrichlorosilane.

from that results according to the invention, for example the first and the second method for producing a chemical Sensors according to the examples 8 and 9 as follows.

Example 8: first method

• a) Reinigung oder
• b) Reinigung, Abscheidung von Messelektroden und Behandlung der Oberfläche beispielsweise nach einem der beiden Verfahren, wie sie in den Beispielen 5 bis 7 beschrieben sind,

dritte Stufe: Herstellung einer Lösung, die gleichzeitig die funktionalisierten Teilchen und die organischen Wechselwirkungsmoleküle enthält, die den Nachweis der chemischen Species gewährleisten,
vierte Stufe: Abscheidung des Materials auf dem Träger,
fünfte Stufe: Abscheidung der Elektroden für den Fall, dass sie nicht in der zweiten Stufe eingeführt worden sind.Perform the following four or five stages:
first step: synthesis of the functionalized nanoparticles as given in example 1, for example
second stage: conditioning the substrate using two options:

• a) cleaning or
• b) cleaning, deposition of measuring electrodes and treatment of the surface, for example, by one of the two methods, as described in Examples 5 to 7,

third stage: preparation of a solution containing at the same time the functionalized particles and the organic interaction molecules which ensure the detection of the chemical species,
fourth stage: deposition of the material on the support,
fifth step: deposition of the electrodes in case they have not been introduced in the second stage.

Example 9: second method

• a) Reinigung oder
• b) Reinigung, Abscheidung der Messelektroden und Behandlung der Oberfläche nach einem der in den Beispielen 5 bis 7 beschriebenen Verfahren,

vierte Stufe: Herstellung einer Lösung, die bepfropfte Teilchen enthält,
fünfte Stufe: Abscheidung des Materials auf dem Träger unter Anwendung einer der oben genannten verschiedenen Methoden und
sechste Stufe: Abscheidung der Elektroden für den Fall, dass diese in der dritten Stufe nicht eingeführt worden sind.Perform the following six or seven stages:
first stage: synthesis of the functionalized nanoparticles, for example as indicated in Example 1,
second step: grafting of the organic interaction molecules, which allow the orientation of the selectivity properties to the functionalized particles, as indicated in Example 2,
third stage: conditioning the substrate using two options:

• a) cleaning or
• b) cleaning, deposition of the measuring electrodes and treatment of the surface according to one of the methods described in Examples 5 to 7,

fourth stage: preparation of a solution containing grafted particles,
fifth step: deposition of the material on the support using one of the abovementioned different methods and
sixth step: deposition of the electrodes in case they have not been introduced in the third stage.

Example 10

Separation of the transduction functions and the detection functions with materials after the first Strategy of the invention have been prepared.

• – Platin-Nanoteilchen, die funktionalisiert worden sind mit 4-Mercaptoanilin,
• – Moleküle von Kobalttetraoctyl-tetraamido-phthalocyanin für den Nachweis der chemischen Species.

The components of the system are as follows:

• Platinum nanoparticles functionalized with 4-mercaptoaniline,
• - Molecules of cobalt tetraoctyl-tetraamido-phthalocyanine for the detection of chemical species.

The selectivity of the device is ensured by the above-mentioned organic molecule, which is the organic interaction molecule. This shows the enclosed 6 , These 6 allows a comparison between the sensitivity of the two sensors according to the invention to nitrogen dioxide. The first sensor, which is the curve 11 corresponds (left ordinate), which includes only the functionalized nanoparticles, is insensitive to NO ₂ gas, the second sensor, that of the curve 13 corresponds to (right ordinate), includes the nanoparticles and the organic interaction molecules that are responsible for the sensitivity of the device to nitrogen dioxide.

Example 11

Separation of Transduction functions and the detection functions with materials, which has been prepared according to the second strategy of the invention are

The particles used in this example are grafted with a thiophene molecule having an acid chloride function (see equation (I) above). The 7 Figure ₄ shows the sensitivity to NO _{2 of} a device consisting of platinum particles which have been readily functionalized with 4-mercaptoaniline (curve 15 ), and from the same particles grafted with the thiophene molecule (curve 17 ). These curves 15 and 17 The responsiveness clearly indicates that the grafting makes the sensor sensitive to NO ₂ , while the same particles not grafted thereto are insensitive to NO ₂ .

Example 12

Orientation of the selectivity of the sensors

The in the 6 and 7 The response curves already shown already show the orientation of the sensitivity to NO ₂ . The results shown in this example relate to the action of vapors of organic molecules.

Sensors made using the two strategies described above were simultaneously exposed to various organic pollutants. The 8th shows an effect of selectivity as a function of the nature of the organic interaction molecules present in the chemical detection film of the present invention.

In Table 1 below shows the nature of the organic interaction molecule in the chemical detection film for each prepared according to the invention Sensor specified.

Table 1

In the 8th corresponds to the curve 19 the sensor 19 , the curve 21 corresponds to the sensor 21 and the like ....

This diagram shows that the sensor 19 sensitive to vapors of chloroform and acetone while the sensor 21 gives no answer (reaction). The sensor 27 shows a change of the signal as opposed to that of the sensor 19 , The sensors 23 and 25 seem to be insensitive to chloroform, but they give a very weak response to acetone.

The 9 shows the influence of other pollutants, toluene, triethylamine, acetic acid on the same sensors. The sensor 19 is sensitive to toluene and acetic acid but not sensitive to triethylamine. The sensor 21 is insensitive to all pollutants. The sensor 23 is insensitive to toluene and to triethylamine, but sensitive to acetic acid. The sensor 25 is sensitive to triethylamine and less sensitive to it sigsäure.

Example 13

Temporal stability of the sensors

The 10 illustrates the electrical stability of hybridized materials made by the first or second method. In this diagram, on the ordinate axis, the ratio R / R ₀ between the temporal durability of the sensor and the durability of the sensor at time t = 0 (initial resistance of the sensor) is indicated. While the purely organic material (curve 29 ) shows a very large deviation, the hybrid material (reference numeral 31 ) a much better temporal electrical resistance.

Example 14

Temporal reliability of the sensors in terms of repeatability ( 11A ) and reproducibility ( 11B )

The Sensors tested in this example comprise a film according to the invention, contains the platinum nanoparticles, which are grafted onto organic mer captoaniline molecules on the organic thiophene molecules has been grafted.

The response curves of a sensor sensitive to NO ₂ were established at a time interval of 9 months. The pollutant is NO ₂ and responsiveness was calculated based on the first exposure. The 11A explains the results of these measurements. In this figure represents the curve 33 the result of the measurements made on May 28, 1997, it shows a deviation of 18%, and the curve 35 is the result of measurements made on February 27, 1997 and shows a deviation of 24%. The sensitivities calculated at the first exposure give a deviation of only 5%.

The response curves of a sensor sensitive to NO ₂ were recorded with two identical sensors made by the method of the invention. The pollutant is NO ₂ and the responsiveness is the one found at the first exposure. The 11B explains the results of these measurements. In this figure, the curves show 37 and 39 the result of the measurements made with these two "identical" sensors according to the invention.

The 11A shows the repeatability of the detection measurements with the passage of time in the same sensor according to the invention and the 11B shows the reproducibility of the detection measurements for two identical sensors according to the invention.

Example 15

Suppression of contact resistance

The 12A shows the change in resistance of a hybrid film according to the invention comprising functionalized particles and organic interaction molecules (curve 41 in the 12A ), and the 12B shows the change in the resistance of a purely organic film as a function of the distance between two measuring electrodes (curve 43 in the 12B ). An estimate of the value for the contact resistance is given by the value on the ordinate at the origin. The 12A shows that the ordinate at the origin, which corresponds to the contact resistance, is negligible, and the 12B shows that the ordinate at the origin, which corresponds to the contact resistance, is not negligible. The presence of the functionalized particles thus makes it possible to make the contact resistance of the devices negligibly small.

Claims (27)

A film for detecting a chemical species containing mineral nanoparticles and organic molecules grafted onto the nanoparticles to form an organic crown around the nanoparticles, characterized in that organic molecules are formed from the interaction between the nanoparticles and the nanoparticles and the chemical species to be detected are mixed with the nanoparticles around which an organic crown has been formed or grafted onto the organic molecules that form an organic crown around the nanoparticles. A film according to claim 1, wherein the nanoparticles comprise at least one member selected from the group consisting of platinum, gold, silver, CdS and TiO ₂ . A film according to claim 1 or 2, wherein the nanoparticles one size with one Have diameters of 1 to 100 nm. A film according to claim 1 or 2, wherein the nanoparticles one size with one Have diameters of 1 to 10 nm. A film according to any one of claims 1 to 4, wherein the organic molecules from the interaction between the film and the one to be detected chemical species a molecule include that selected is from a group comprising a phthalocyanine, a tetrapyridinophthalocyanine, a thiophene, an oligothiophene, a porphyrin, an erythrosin, a crown ether, an azacrown ether, a cryptophan, a cyclodextrin, a linear or branched alkyl having 1 to 12 carbon atoms, a benzene or a derivative of these molecules that is unsubstituted or are substituted by one or more chemical functions an interaction with the chemical species to be detected. A film according to any one of claims 1 to 5, wherein the the nanoparticles grafted organic molecules bifunctional molecules represent, on the one hand, at least one chemical function for Fixation on the nanoparticles and on the other hand at least one chemical function to form a bond with the organic molecules from the interaction between the film and the one to be determined have chemical species. A film according to any one of claims 1 to 5, wherein the organic molecules which form an organic crown around the nanoparticles molecule include that selected is from a group that includes a linear or branched one Alkyl having 1 to 12 carbon atoms or an aryl, which by a or multiple chemical functions for attachment to the nanoparticles is substituted. A film according to claim 6 or 7, wherein the at least a chemical function is selected for fixation on the nanoparticles from a group containing a thiolate, an isonitrile, an amine, a Trioctyl phosphate and a pyridine. A film according to claim 6 or claim 8, when this depends on the claim 6, wherein the at least one chemical function to form a bond with the organic molecules from the interaction between the film and the one to be detected selected chemical species is from a group comprising a pyridine function, an amine function, a carboxylate function, an acid function, an alcohol function, an aldehyde function, an isocyanate function, an isothiocyanate function, an ester function and a COCl function. A film according to claim 5 or 8, when used by the Claim 6 or 9 depends wherein the at least one chemical function is an interaction is selected with the chemical species to be detected from a group comprising an amine function, a carboxylate function, an acidity function, an alcohol function, an aldehyde function, an isocyanate function, an isothiocyanate function and an ester function. A film according to claim 6, wherein the organic bifunctional molecules a molecule include that selected is from a group that includes a thiophenol, a linear or branched alkylthiol having 1 to 11 carbon atoms and an arylthiol. A film according to any one of claims 1 to 4, wherein the the nanoparticles are selected from grafted organic molecules from a group comprising 4-mercaptoaniline, 4-mercaptopyridine, N-aminoalkanethiol, mercaptohydroxyalkane or a mixture thereof. A film according to claim 1, wherein the nanoparticles are platinum nanoparticles and on the platinum nanoparticles are organic molecules of 4-mercaptoaniline grafted on. A film according to claim 13, wherein organic molecules of thiophene or erythrosin grafted onto the 4-mercaptoaniline molecules. A film according to claim 13, which further comprises a tetrapyridinophthalocyanine includes. A film according to any one of the preceding claims, wherein the nanoparticles alternate with organic molecules in the way that a homogeneous mixture in the nanometer range is formed. Method for producing a chemical sensor, an insulating substrate, a film to detect a chemical Species and at least one metal electrode, characterized in that the method includes a step of producing a film according to any one of claims 1 to 16, a stage for depositing this film on the insulating Substrate and a step for depositing the metal electrode (s) either on the insulating substrate before the deposition of the film or on the film after the deposition of the latter on the insulating Substrate comprises. The method of claim 17, wherein the electrodes deposited prior to deposition of the film on the insulating substrate become. The method of claim 17 or 18, further comprising Stage that then consists of being at the interface between the insulating substrate and the film and / or at the interface between the Electrodes and the film at least one monomolecular intercalation layer forms, which consists of molecules, which have an organic group which has the properties of a mechanical and / or electrical contact between the film and the metal electrodes and / or between the film and the substrate can improve. The method of claim 19, wherein the molecules of the intercalation layer, the at the interface is arranged between the substrate and the film, here as the first molecules referred to, by the molecules the intercalation layer, which is at the interface between the metal electrodes and the film, here referred to as second molecules, are different. The method of claim 20, wherein the first molecules by means of Silicon atoms are bound to the insulating substrate and the second molecules bound to the electrodes by means of sulfur or nitrogen atoms become. A method according to any one of claims 17 to 21, wherein the deposition of the film, which is done by vertical transfer using a solution of nanoparticles and organic molecules containing one or more amphiphilic ones molecules include. Chemical sensor, characterized in that an insulating substrate, a film according to any one of claims 1 to 16 and at least one measuring electrode made of metal. A chemical sensor according to claim 23, wherein at least a measuring electrode made of metal between the insulating substrate and the film is arranged. A chemical sensor according to claim 23 or 24, which Furthermore at the interface between the substrate and the film at least one monomolecular Intercalation layer, which consists of organic molecules, covalently bonded to the substrate or electrodes are, being the molecules have an organic group which the mechanical and / or electrical contact properties between the film from the active Material and the metal electrodes and between the film from the active Improve material and the substrate. A chemical probe according to claim 25, wherein the organic Group of molecules the intercalation layer selected is composed of hydrophilic groups, hydrophobic groups and groups form a chemical bond with the film. A chemical sensor according to claim 25 or 26, wherein the molecules the intercalation layer, which is at the interface between the substrate and the film, here referred to as the first molecules, of the molecules of the Intercalation layer, which is at the interface between the electrodes and the film, here referred to as second molecules, are different.